Narcissists very rarely commit suicide. They react with suicidal ideation and reactive psychoses to severe stress -- but to commit suicide runs against the grain of narcissism. This is more of a Borderline (BPD) behavior. The differential diagnosis of NPD from BPD rests on the absence of attempted suicide and self-mutilation in NPD.
In response to a life crisis (divorce, public disgrace, imprisonment, accident, bankruptcy, terminal or disfiguring illness) the narcissist is likely to adopt either of two reactions.
(From the book "Malignant Self-love: Narcissism Revisited" by Sam Vaknin - Click on this link to purchase the print book, or 16 e-books, or 2 DVDs with 12 hours of video lectures on narcissists, psychopaths, and abuse in relationships: http://www.narcissistic-abuse.com/thebook.html)